The invention relates to a pressure regulator with a closing member, and in particular, to a pressure regulator with a closing member on which is supported a valve spring which bears with its other end against an upper end face of a spring can.
Pressure regulators are typically installed, for example, in present-day motor vehicles For many applications, it is necessary that the opening force of the closing member of the pressure regulator, and therefore the pressure regulated by the regulator, are as exact as possible despite unavoidable manufacturing, tolerances. This is accomplished during manufacture by a calibrating operation. During this operation, a check is made as to the pressure at which the pressure regulator opens. Then, in order to set the pressure point, the end face of the spring can is pressed into the spring can such that the valve spring is appropriately tensioned.
It has been shown, however, that such regulators can be calibrated only in a complicated way and with relatively high inaccuracies. This is, primarily, because the spring can pressed in on the end face, after being pressed in, inevitably springs back by an amount resulting from material elasticities. It is therefore necessary, during the pressing-in operation, to overrun the calibrating point somewhat and hope that, after the springback, the correct opening pressure is obtained. It is not possible, in this case, to avoid a situation where the pressed-in portion occasionally springs back less than expected and too high an opening pressure is therefore set. Such a fault can no longer be rectified subsequently by recalibration.
The invention discloses a pressure regulator such that it is possible to carry out calibration which is as accurate as possible.
In one embodiment of the invention, the spring can includes a casing part and a lid. The lid is connected to the casing surface of the casing part in a position fixing a desired spring force.
During the calibrating operation, the lid can be displaced axially relative to the casing part until the desired spring force is set, the lid then being connected to the casing part. Since this connection is made on the casing surface of the casing part, the lid will not spring back, so that the spring force can be set very accurately.
In an alternative embodiment, the lid can be designed as a component to be slipped over the casing part or as a component bridging the casing part. It is configured in a particularly simple way if it is pushed into the casing part and comes to bear with a flanged edge against the casing surface on the inside.
In another embodiment, the lid can be connected to the casing part in very different ways, for example by means of screws or rivets leading radially into the casing part or by welding, soldering or adhesive bonding. A very simple connection is obtained when, according to another embodiment of the invention, the casing surface of the casing part has indentations engaging into the edge of the lid.
In still another embodiment, the lid can be connected to the casing part particularly accurately in the position found during calibration, when the indentations are individual tabs which are formed by U-shaped incisions into the casing surface and by pressing the material delimited by the incisions into the edge of the lid.
Alternatively, the indentations may be formed by protuberances in the form of a spherical cap, the protuberances of the casing surface of the casing part and of the edge engaging into each other.